[llvm] faf3333 - [SCEV] Add coverage for flag inference with vscale strided IVs
Philip Reames via llvm-commits
llvm-commits at lists.llvm.org
Wed Jul 31 09:49:35 PDT 2024
Author: Philip Reames
Date: 2024-07-31T09:48:44-07:00
New Revision: faf3333510e0c2c3f319af40456e10c471e11ce8
URL: https://github.com/llvm/llvm-project/commit/faf3333510e0c2c3f319af40456e10c471e11ce8
DIFF: https://github.com/llvm/llvm-project/commit/faf3333510e0c2c3f319af40456e10c471e11ce8.diff
LOG: [SCEV] Add coverage for flag inference with vscale strided IVs
Given vscale is a power of two, we should be able to prove no-self-wrap
in these cases. We currently don't, but an upcoming change will fix this.
Added:
Modified:
llvm/test/Analysis/ScalarEvolution/trip-count-scalable-stride.ll
Removed:
################################################################################
diff --git a/llvm/test/Analysis/ScalarEvolution/trip-count-scalable-stride.ll b/llvm/test/Analysis/ScalarEvolution/trip-count-scalable-stride.ll
index befcabd911467..943389d07eb8b 100644
--- a/llvm/test/Analysis/ScalarEvolution/trip-count-scalable-stride.ll
+++ b/llvm/test/Analysis/ScalarEvolution/trip-count-scalable-stride.ll
@@ -362,3 +362,165 @@ for.body: ; preds = %entry, %for.body
for.end: ; preds = %for.body, %entry
ret void
}
+
+; The next two cases check to see if we can infer the flags on the IV
+; of a countup loop using vscale strides.
+; TODO: We should be able to because vscale is a power of two and these
+; are finite loops by assumption.
+
+define void @vscale_slt_noflags(ptr nocapture %A, i32 %n) mustprogress vscale_range(2,1024) {
+; CHECK-LABEL: 'vscale_slt_noflags'
+; CHECK-NEXT: Classifying expressions for: @vscale_slt_noflags
+; CHECK-NEXT: %vscale = call i32 @llvm.vscale.i32()
+; CHECK-NEXT: --> vscale U: [2,1025) S: [2,1025)
+; CHECK-NEXT: %i.05 = phi i32 [ %add, %for.body ], [ 0, %entry ]
+; CHECK-NEXT: --> {0,+,vscale}<%for.body> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT: %arrayidx = getelementptr inbounds i32, ptr %A, i32 %i.05
+; CHECK-NEXT: --> {%A,+,(4 * vscale)<nuw><nsw>}<%for.body> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT: %add = add i32 %i.05, %vscale
+; CHECK-NEXT: --> {vscale,+,vscale}<%for.body> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT: Determining loop execution counts for: @vscale_slt_noflags
+; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %for.body: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %for.body: Unpredictable symbolic max backedge-taken count.
+;
+entry:
+ %vscale = call i32 @llvm.vscale.i32()
+ %cmp4 = icmp sgt i32 %n, 0
+ br i1 %cmp4, label %for.body, label %for.end
+
+for.body: ; preds = %entry, %for.body
+ %i.05 = phi i32 [ %add, %for.body ], [ 0, %entry ]
+ %arrayidx = getelementptr inbounds i32, ptr %A, i32 %i.05
+ %0 = load <vscale x 4 x i32>, ptr %arrayidx, align 4
+ %inc = add nsw <vscale x 4 x i32> %0, splat (i32 1)
+ store <vscale x 4 x i32> %inc, ptr %arrayidx, align 4
+ %add = add i32 %i.05, %vscale
+ %cmp = icmp slt i32 %add, %n
+ br i1 %cmp, label %for.body, label %for.end
+
+for.end: ; preds = %for.body, %entry
+ ret void
+}
+
+define void @vscalex4_ult_noflags(ptr nocapture %A, i32 %n) mustprogress vscale_range(2,1024) {
+; CHECK-LABEL: 'vscalex4_ult_noflags'
+; CHECK-NEXT: Classifying expressions for: @vscalex4_ult_noflags
+; CHECK-NEXT: %vscale = call i32 @llvm.vscale.i32()
+; CHECK-NEXT: --> vscale U: [2,1025) S: [2,1025)
+; CHECK-NEXT: %VF = mul i32 %vscale, 4
+; CHECK-NEXT: --> (4 * vscale)<nuw><nsw> U: [8,4097) S: [8,4097)
+; CHECK-NEXT: %i.05 = phi i32 [ %add, %for.body ], [ 0, %entry ]
+; CHECK-NEXT: --> {0,+,(4 * vscale)<nuw><nsw>}<%for.body> U: [0,-3) S: [-2147483648,2147483645) Exits: <<Unknown>> LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT: %arrayidx = getelementptr inbounds i32, ptr %A, i32 %i.05
+; CHECK-NEXT: --> {%A,+,(16 * vscale)<nuw><nsw>}<%for.body> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT: %add = add i32 %i.05, %VF
+; CHECK-NEXT: --> {(4 * vscale)<nuw><nsw>,+,(4 * vscale)<nuw><nsw>}<%for.body> U: [0,-3) S: [-2147483648,2147483645) Exits: <<Unknown>> LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT: Determining loop execution counts for: @vscalex4_ult_noflags
+; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %for.body: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %for.body: Unpredictable symbolic max backedge-taken count.
+;
+entry:
+ %vscale = call i32 @llvm.vscale.i32()
+ %VF = mul i32 %vscale, 4
+ %cmp4 = icmp sgt i32 %n, 0
+ br i1 %cmp4, label %for.body, label %for.end
+
+for.body: ; preds = %entry, %for.body
+ %i.05 = phi i32 [ %add, %for.body ], [ 0, %entry ]
+ %arrayidx = getelementptr inbounds i32, ptr %A, i32 %i.05
+ %0 = load <vscale x 4 x i32>, ptr %arrayidx, align 4
+ %inc = add nsw <vscale x 4 x i32> %0, splat (i32 1)
+ store <vscale x 4 x i32> %inc, ptr %arrayidx, align 4
+ %add = add i32 %i.05, %VF
+ %cmp = icmp ult i32 %add, %n
+ br i1 %cmp, label %for.body, label %for.end
+
+for.end: ; preds = %for.body, %entry
+ ret void
+}
+
+; The next two cases check to see if we can infer the flags on the IV
+; of a countdown loop using vscale strides.
+; TODO: We should be able to because vscale is a power of two and these
+; are finite loops by assumption.
+
+define void @vscale_countdown_ne(ptr nocapture %A, i32 %n) mustprogress vscale_range(2,1024) {
+; CHECK-LABEL: 'vscale_countdown_ne'
+; CHECK-NEXT: Classifying expressions for: @vscale_countdown_ne
+; CHECK-NEXT: %vscale = call i32 @llvm.vscale.i32()
+; CHECK-NEXT: --> vscale U: [2,1025) S: [2,1025)
+; CHECK-NEXT: %start = sub i32 %n, %vscale
+; CHECK-NEXT: --> ((-1 * vscale)<nsw> + %n) U: full-set S: full-set
+; CHECK-NEXT: %iv = phi i32 [ %sub, %for.body ], [ %start, %entry ]
+; CHECK-NEXT: --> {((-1 * vscale)<nsw> + %n),+,(-1 * vscale)<nsw>}<%for.body> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT: %arrayidx = getelementptr inbounds i32, ptr %A, i32 %iv
+; CHECK-NEXT: --> {((4 * %n) + (-4 * vscale)<nsw> + %A),+,(-4 * vscale)<nsw>}<%for.body> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT: %sub = sub i32 %iv, %vscale
+; CHECK-NEXT: --> {((-2 * vscale)<nsw> + %n),+,(-1 * vscale)<nsw>}<%for.body> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT: Determining loop execution counts for: @vscale_countdown_ne
+; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %for.body: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %for.body: Unpredictable symbolic max backedge-taken count.
+;
+entry:
+ %vscale = call i32 @llvm.vscale.i32()
+ %cmp4 = icmp sgt i32 %n, 0
+ %start = sub i32 %n, %vscale
+ br i1 %cmp4, label %for.body, label %for.end
+
+for.body: ; preds = %entry, %for.body
+ %iv = phi i32 [ %sub, %for.body ], [ %start, %entry ]
+ %arrayidx = getelementptr inbounds i32, ptr %A, i32 %iv
+ %ld = load <vscale x 4 x i32>, ptr %arrayidx, align 4
+ %inc = add nsw <vscale x 4 x i32> %ld, splat (i32 1)
+ store <vscale x 4 x i32> %inc, ptr %arrayidx, align 4
+ %sub = sub i32 %iv, %vscale
+ %cmp = icmp ne i32 %sub, 0
+ br i1 %cmp, label %for.body, label %for.end
+
+for.end: ; preds = %for.body, %entry
+ ret void
+}
+
+define void @vscalex4_countdown_ne(ptr nocapture %A, i32 %n) mustprogress vscale_range(2,1024) {
+; CHECK-LABEL: 'vscalex4_countdown_ne'
+; CHECK-NEXT: Classifying expressions for: @vscalex4_countdown_ne
+; CHECK-NEXT: %vscale = call i32 @llvm.vscale.i32()
+; CHECK-NEXT: --> vscale U: [2,1025) S: [2,1025)
+; CHECK-NEXT: %VF = shl i32 %vscale, 2
+; CHECK-NEXT: --> (4 * vscale)<nuw><nsw> U: [8,4097) S: [8,4097)
+; CHECK-NEXT: %start = sub i32 %n, %VF
+; CHECK-NEXT: --> ((-4 * vscale)<nsw> + %n) U: full-set S: full-set
+; CHECK-NEXT: %iv = phi i32 [ %sub, %for.body ], [ %start, %entry ]
+; CHECK-NEXT: --> {((-4 * vscale)<nsw> + %n),+,(-4 * vscale)<nsw>}<%for.body> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT: %arrayidx = getelementptr inbounds i32, ptr %A, i32 %iv
+; CHECK-NEXT: --> {((4 * %n) + (-16 * vscale)<nsw> + %A),+,(-16 * vscale)<nsw>}<%for.body> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT: %sub = sub i32 %iv, %VF
+; CHECK-NEXT: --> {((-8 * vscale)<nsw> + %n),+,(-4 * vscale)<nsw>}<%for.body> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT: Determining loop execution counts for: @vscalex4_countdown_ne
+; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %for.body: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %for.body: Unpredictable symbolic max backedge-taken count.
+;
+entry:
+ %vscale = call i32 @llvm.vscale.i32()
+ %VF = shl i32 %vscale, 2
+ %cmp4 = icmp sgt i32 %n, 0
+ %start = sub i32 %n, %VF
+ br i1 %cmp4, label %for.body, label %for.end
+
+for.body: ; preds = %entry, %for.body
+ %iv = phi i32 [ %sub, %for.body ], [ %start, %entry ]
+ %arrayidx = getelementptr inbounds i32, ptr %A, i32 %iv
+ %ld = load <vscale x 4 x i32>, ptr %arrayidx, align 4
+ %inc = add nsw <vscale x 4 x i32> %ld, splat (i32 1)
+ store <vscale x 4 x i32> %inc, ptr %arrayidx, align 4
+ %sub = sub i32 %iv, %VF
+ %cmp = icmp ne i32 %sub, 0
+ br i1 %cmp, label %for.body, label %for.end
+
+for.end: ; preds = %for.body, %entry
+ ret void
+}
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